U.S. patent number 3,993,935 [Application Number 05/533,396] was granted by the patent office on 1976-11-23 for printed circuit board connection.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to George J. Leiby, Lewis A. Phillips.
United States Patent |
3,993,935 |
Phillips , et al. |
November 23, 1976 |
Printed circuit board connection
Abstract
A printed circuit board or the like for electrical apparatus has
edge connectors for insertion into a terminal or group of terminals
for communication of electrical signals from the terminals to the
board and vice versa. Some contacts on the board edge are recessed
slightly from the edge so that certain electrical connections may
be made prior to others.
Inventors: |
Phillips; Lewis A. (Rockville,
MD), Leiby; George J. (Mount Airy, MD) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
24125775 |
Appl.
No.: |
05/533,396 |
Filed: |
December 16, 1974 |
Current U.S.
Class: |
361/748; 361/785;
361/752; 439/924.1; 439/59 |
Current CPC
Class: |
H05K
1/117 (20130101); H01R 12/721 (20130101); H05K
2201/0746 (20130101); H05K 2201/094 (20130101) |
Current International
Class: |
H05K
1/11 (20060101); H05K 001/04 () |
Field of
Search: |
;339/14R,14P,111,776MP
;317/11B,11C,11DH |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith, Jr.; David
Claims
What is claimed is:
1. A printed circuit board having electrical components thereon,
means for applying electrical signals to said board and for
extracting electrical signals from said board said means
comprising:
a. a plurality of terminal connectors along at least one edge of
said board,
b. at least one of said terminal connectors recessed from the edge
of said board,
c. at least one of said terminal connectors extending to the edge
of said board,
d. a connector receptacle for receiving said edge of said board and
said terminal connectors, whereby said terminal connector extending
to the edge of said board makes contact with said connector
receptacle prior to contact between said connector receptacle and
said recessed terminal connector, and
e. a signal path extending from said receptacle at one end of said
board edge, onto said board and along said board to the opposite
end thereof and through a recessed terminal connector to said
receptacle to prevent signal connection when the board is inserted
into the receptacle in a skewed manner.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to module boards, and more particularly to
providing module board connection means such that a board may be
inserted into or removed from its receptical without interfering
with the operation of other boards connected in the same
circuit.
2. Description of the Prior Art
In many electronic devices, circuit boards are utilized to carry
components and sub-assemblies of electronic circuits. In some
electronics applications, for example in the field of digital
computers, redundant or parallel-connected circuits may be used to
aid in maintaining reliability or providing ease of maintenance of
the devices. In such applications, it is frequently desirable to
provide the facility for removing certain of the circuit boards
while the device is in operation without disturbing the operation
of the remainder of the boards.
SUMMARY OF THE INVENTION
In order to provide for removal and insertion of circuit boards
during operation of the device of which the board is a component,
the instant invention provides recessed contacts in certain
critical board edge connection functions such as to allow
stabilization of the board elements and signals before electrical
contact is made to the particularly critical circuit element.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially pictorial, partially schematic representation
of a printed circuit board according to the instant invention.
FIG. 2 is a timing diagram representing signal and voltage
connections as a function of time for a typical application of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a partially pictorial, partially schematic diagram of
a printed circuit board according to the instant invention, which
board may form a portion of a data communications device. In FIG.
1, a printed circuit board, in this case a two-sided printed
circuit board, is shown generally at 2. On the right hand side of
the Printed CCircuit Board 2 are shown Connector Tabs 4, 6, 8, 10,
12, 13, and 14 which are used in conjunction with socket pins shown
schematically, to apply voltages and/or electrical signals to or
from the board and the components mounted thereon. It should be
noted that Connector Tabs 4 and 6 extend to the very edge of the
printed circuit board while Connector Tabs 8, 10, 12, 13, and 14
are slightly recessed from the edge of the board. Since the board
represented is a two-sided board, that is, signals and/or voltages
may be applied to either side of the printed circuit board, a
further set of Terminals 22, 24, 16, 18, 20, 26, and 28 are
provided, of which Terminals 16, 18 and 20 extend to the edge of
the board and 22, 24, 26, and 28 are slightly recessed on the
opposite side of the board.
A number of additional terminals and contacts may be provided on a
typical board, for grounding and for other signals and voltages,
but these are not shown in this pictorial/schematic diagram for
purposes of clarity of description.
Mounted on the board are several integrated circuit devices
including an LSI P-Channel Control Logic and Data Buffering Device
30, open collector output circuits (such as integrated curcuit type
32, and integrated circuits containing drivers and receivers which
may be, for example, interconnected to other data communications
equipment and are represented at 34.
The LSI P-Channel Circuit 30 may use a technique for interfacing
with TTL logic both from on and off the board. This technique may
require that the LSI substrate be connected to a plus 5 volt
supply. Until the plus 5 volt supply on the board has made
connection to the plus 5 volt supply bus, a Capacitor 36 will be
discharged and the substrate of the LSI Circuit 30 will be held
near ground potential. Since bus signals which must connect
directly to the LSI Module 30 go positive to about plus 3.5 volts,
FET junctions in the LSI would be forward biased and load the input
bus for each connection. The loading could be excessive and
interfere with signals to other boards. Direct inputs to the LSI
Module 30 are thus delayed via the Recess Contact 13 until after
the plus 5 volts is applied by means of an unrecessed contact 20 to
plus 5 volts through Contacts 20 and 18.
Shown to the right of the Printed Circuit Board 2 are schematic
representations of bus and signals terminals to be applied to the
board. For example, the plus 5 volt supply bus is shown for
connection with Contacts 20 and 18 on the board. A reset bus is
shown with a contact for connection to contact 16 and an output bus
is shown with a connector for contact with the Contact 4 on the
board. Additionally, jumper contacts are provided for the recessed
terminals on the board and are shown at 38, 40 for connection to
Tabs 14 and 28, respectively, a Jumper 42, 44 for connection to
recessed Tabs 10 and 24, and a Jumper 46, 48 for connection to
recessed Tabs 8 and 22, respectively. As can be seen, these jumpers
are provided to allow connection between the pairs of tabs of which
each is associated.
Output bus signals share output bus lines from other channel
boards. The open Collector Output Circuits 32 which drive these bus
lines are disabled until the series circuit through jumpers 46, 48
and 38, 40 connects the plus 5 supply volts to them. When the
module first starts entering the connector, the Reset Line which
normalizes all controls in the LSI 30 is driven high (Reset true)
by a Biasing Resistor 50 connected to plus 5 volts. Only after all
the logic has settled into a quiescent state during module
insertion will the plus 5 volt supply bus be connected to the
output driver circuits. It should be noted that, because associated
jumper connectors are located on opposite ends of the Printed
Circuit Board 2, that an insertion in a skewed manner will not
allow the connection of the plus 5 volt supply until the board is
properly seated fully in the connector block.
A series circuit through Connections 42, 44 and 12, 26 must connect
the Reset bus to the Reset Line on the board to ground out the
positive biasing from Resistor 50 before any operation can
begin.
After the board reaches the bottom of the connector socket, and all
contacts are made, the board may receive control signals. The input
Control Module Select (L) is held high when none of the channels on
the module are selected to receive control signals to begin
operation. During board insertion this signal would be held high
(unselected) until the installer knows that the board is seated
sufficiently to be sure all recessed contacts can accept control
codes correctly.
As previously noted, there are many ground contacts not shown in
the sketch, and at least two plus 5 volt supply contact (18 and 20)
arranged with a minimum of one plus 5 volt and one ground along the
top and bottom halves of the board edge. These contacts are not
recessed enabling connection to both ground and the plus 5 volt
supply before connection is made to any of the recessed contact
used for direct input to the LSI. The sequence is equally
maintained using typical manufacturing tolerances, and the
resulting skew allowance during insertion. Capacitor C2 limits
transients caused by the connection of the output bus to the output
circuit which has a finite capacitance to be charged from the bus
during the connection.
FIG. 2 is a timing diagram showing the relationship among voltages
and signals provided to and from the Printed Circuit Board 2. As
the board insertion sequence is begun, the Reset bus produces Reset
pulses from the remaining portions of the communications system of
which this board is a part. The Reset Line, the plus 5 volt supply
and the control module select (L) may all be high as generated by
other modules not shown. As the board makes initial contact, at A,
and the Reset plus 5 volt supplies together with the Control Module
Select (L) are all applied to the devices on the printed circuit
board. As the board becomes fully seated at B, the plus 5 volts
seated supply voltage may be applied to the open collector output
Circuits 32. The Reset will also be applied to the LSI P-Channel
Module 30 as a result of the recessed Contact 10, 24, 12 and 26. As
previously noted, the plus 5 volt supply has been immediately
established in connection with the LSI P-Channel 30 as a result of
the non-recessed Contacts 18 and 20. The direct input connection
via recessed Terminal 13 may then be applied to the LSI P-Channel
Module 30 and when the Control Module Select Line (L) goes low,
full control is given to the module at C on the timing diagram. The
module is, at this point, prepared to assume full operation.
In summary, when a module board is inserted in a receptacal, and is
being pushed toward the bottom, an arrangement of single and
multiple contacts, some of them recessed, determine a sequence of
connections to eliminate interference with other parallel channels
of the device which may be in operation.
While the present invention has been described with reference to a
preferred arrangement thereof, it will be understood to those
skilled in the art that various changes may be made without
departing from the true spirit and scope of the invention as set
forth in the appended claims.
* * * * *